Researchers at the University of Maryland Center for Environmental Science are studying climate adaptation of forest trees. We need volunteers throughout the U.S. and Canada to monitor seasonal changes in the two target poplar trees - Balsam poplar and Quaking aspen! PopClock researchers will compare your on-the-ground observations of poplar trees to satellite images and will then combine these results with genetic information to identify areas where these trees are most and least adapted to climate change. Please select "wild" trees—that is, trees that have not been intentionally planted by humans. If possible, look for a group of one species or the other; if you can't find a group, observations of individual trees are fine.